P -wave resonant state of the HeΣ4 hypernucleus in the He4(K−,π−) reaction

We theoretically investigate a possible existence of a p  -wave HeΣ4 resonant state with Jπ=1−Jπ=1−, T≃1/2T≃1/2 above the Σ   threshold, using a coupled (3N–Λ)+(3N–Σ)(3N–Λ)+(3N–Σ) model with a spreading potential. We calculate inclusive and Σ–Λ   conversion π−π− spectra in a He4(K−,π−) reaction at 1.5 GeV/c  , θlab=4–12°θlab=4–12° by the Green's function method in a distorted-wave impulse approximation. The pole position for the p-wave Σ   resonant state in HeΣ4 is determined on the Riemann sheets in the complex E   plane. The result shows that a peak of the HeΣ4 resonant state is clearly obtained in the conversion spectra above the Σ   threshold, and that the angular distributions of these spectra enable extraction of the contribution of the resonant state from the π−π− spectra. Effects of the Σ-nucleus potential and the interference between Λ and Σ on the spectra are also discussed.